1. Field of the Invention
The present invention relates generally to a face mask of the type used in airway management in the anesthesiology, critical care, emergency medicine and resuscitation fields, and in particular relates to an ergonomically shaped face mask (EFM) with increased comfort and adherence to the operator""s hand.
2. Description of the Related Art
The symmetrical face mask dome was first developed in the middle of the 19th century, and was designed for spontaneously breathing patients. The first face mask was designed for anesthetic purposes, whereby anesthetic gasses were administered passively through the face mask to spontaneously breathing patients in a sitting position. While the dome was sufficient for that purpose, its symmetrical nature presents challenges when providing positive pressure ventilation to a patient who isn""t breathing, especially when the operator has only one hand available for the mask.
The face mask used in anesthesia, emergency medicine, critical care and resuscitation is a device through which oxygen or anesthetic gasses are administered under positive pressure to a patient. Positive pressure mask ventilation allows the forceful, active administration of oxygen and/or anesthetic gasses from a source to a non-breathing patient. Typically, the attending physician or rescuer (hereinafter collectively referred to as the operator) uses a bag-mask device and holds the face mask with the left hand and squeezes the bag (develop positive pressure air flow) with the right hand.
Several factors contribute to the success of positive pressure mask ventilation. For example, the patient""s facial bone structure affects the quality of the seal between the mask and the face, it being appreciated that an unlimited variety of facial sizes and shapes exist. Accordingly, it is desirable to provide a mask that is capable of forming a reliable seal with several facial structures.
Thus, the specific design characteristics of the face mask also contribute to the success of the mask ventilation. Referring to FIG. 1, a conventional symmetrical face mask 10 is illustrated of the type used by anesthesiologists, paramedics, EMS personal, firefighters, ER personal and anybody involved in artificial ventilation. The two primary components of the face mask 10 include a cuff 11 at its base, and a symmetrical dome 22 extending upwardly from the cuff. The cuff 11 makes direct contact with the face of the patient during ventilation. The dome 22 is used by the operator to grip and seal the mask to the patient""s face, and typically has a (left-right) symmetrical appearance. The dome 22 has a connector 20 for administering the gas from the source to the patient.
Thus, the ventilation technique also contributes to the success of positive pressure mask ventilation. While bag-mask ventilation is a complex technique that requires considerable skill and practice, the complexity is further increased when attempting to provide performing ventilation using one hand. A good face-mask seal is achieved by applying and corroborating two simultaneous forces. In particular, an upper pressure is applied on the dome and a lower pressure is applied to the patient""s jaw. The upper forces are developed as the hand holds the mask with the thumb and index finger around the connector.
Three asymmetrical pressure areas are developed on the dome by the first and second fingers and the palm. The contact area of an operator""s left hand on the mask 10 is identified generally by hatching 18. The tip of the index finger applies pressure to the right side of the dome at location 14, and the palm applies pressure to the left side of the dome at location 16. These pressure areas are connected as the left palm makes full contact with the dome (FIG. 1). The thumb engages the right side of the dome at location 12. The lower pressure forces are developed by the middle, ring, and small fingers as they pull the patient""s jaw and the face mask together. The airway of a patient may be opened by applying a xe2x80x9cjaw thrustxe2x80x9d maneuver, which is especially critical when the patient is unconscious and the tongue obstructs the airway. If the jaw thrust maneuver is unsuccessful, the ventilation will fail regardless of the quality of seal between the mask and the patient""s face.
The application of symmetrical pressure on the face mask is much more difficult when only one hand is used to position the face mask and maintain an open airway while the other hand is being used to squeeze the bag. In the example illustrated, the thumb and the tip of the index finger applies the majority of the pressure on the right side of the mask 10, while the palm and remaining fingers apply pressure to the left side of the mask. With the hand gripping the mask 10 in this position, it is apparent that a user would naturally apply asymmetrical forces to the symmetrical mask. Considering the asymmetrical forces necessary to be applied with the left hand on a symmetrical face mask, the seal is usually lost on the right side of the mask.
When using conventional face masks with one hand, the operator""s hand position is therefore required to be substantially horizontal, with the wrist and forearm twisted out of their natural and relaxed position. In order to generate a sufficient grip in this position, the fingers are forced to assume a xe2x80x9cclaw-likexe2x80x9d posture. This non-neutral position is uncomfortable, tiring, and painful especially when increased force is necessary to obtain and maintain a seal. The user also may need to change his/her grip several times, and may become fatigued, especially with sub-optimal results in ventilation. This can lead to poor oxygenation of the patient and pollution of the operating room with anesthetic gasses. Furthermore, the grip is typically realized between two smooth surfaces, in particular a gloved hand and the symmetrical dome. The situation becomes critical when secretions and blood make the smooth surfaces slippery due to face trauma, vomitus, excessive secretions, and the like.
Due to the difficulties associated with delivering positive pressure mask ventilation with one hand, the Basic Life Support (BLS) for Health Care Providers and the Guidelines 2000 for Cardiopulmonary Resuscitation- CPR and Emergency Cardiovascular Care recommend the two-rescuer use of the bag-mask. In particular, one operator is designated to properly position and hold the mask on the patient""s face with two hands, while the other operator is responsible for squeezing the bag. Two hands may therefore be used in applying symmetrical pressures on the symmetrical face mask to ensure an adequate seal. However, this technique is only useful when two trained rescuers are available to manage the ventilation of the patient. In an overwhelming number of cases, however, one rescuer is forced to perform one-hand ventilation.
Improvements to positive pressure ventilation are only partially addressed by prior art. The majority of improvements made to the face mask were primarily aimed at improving the patient""s comfort. As a result, face masks were produced having an inflatable and ergonomically shaped cuff that better conform to facial features, such as the chin curve. The quality of the seal between the face mask and the patient""s face was still dependent upon a correct ventilation technique with the mask. The prior art fails to address the ergonomic aspect of hand-mask interaction.
For example, European patent application 0427474A2, published May 15, 1991 and entitled xe2x80x9cFace masks and face masks componentsxe2x80x9d describes a face mask and face mask components used in ventilation. In particular, a water-activated hydrophilic polyurethane foam provides a cushion to minimize discomfort to the wearer. EP 0427474 A2 acknowledges that, while face plates typically found in conventional face masks are smooth to minimize discomfort to the wearer, they do not provide a means for the user to achieve a secure grip on the mask. A thumb grip is thus provided that provides a hook for the positioning of the thumb. However, the thumb encircles the hook and does not reach maximally on the right side of the mask. As a result, the seal on the right side will be lost by poor technique. The operator will thus be forced to place the rest of the hand in a non-neutral position with twisting of the hand and the forearm so as to engage the mask in a xe2x80x9cclawxe2x80x9d like grip. EP 0427474 A2 does not therefore address the difficulty associated with attempting to form a tight seal by applying asymmetrical pressure onto a symmetrical face mask, and further does not address the need to establish suitable upper and lower pressures to provide a tight seal with the patient""s face.
International patent publication WO 97/07847, entitled xe2x80x9cAnesthesia Mask,xe2x80x9d discloses a symmetrical face mask is disclosed having one or more circumferential grippers located, for example, above and/or below the inlet port that is said to provide a firm grip to an operator who is dispensing anesthesia to the patient. However, not only do the grippers increase the complexity of and expense of production, WO 97/07847 disregards that a proper mask technique (e.g. upper and lower pressure) is necessary to establish a reliable seal between the mask and the patient""s face. A xe2x80x9cfirm gripxe2x80x9d on the mask does not necessarily correlate to functional upper pressure needed to produce a reliable seal with the patient""s face.
WO 97/07847 discloses straps provided on the mask that are said to develop bilateral and symmetrical traction in an effort to improve the seal between the mask and the patient""s face. However, the face straps only assist in developing upper pressure. Independent lower forces to pull the jaw in the mask and to realize the jaw thrust are therefore still necessary. Furthermore, the presence of the face straps or adjuncts on the face mask to accept these straps impede a sound grip and contact of the hand with the face mask. Moreover, the grippers are designed to keep the hand away from the strap holders, thus limiting the placement of the gripper(s) and corresponding pressure during operation.
What is therefore needed is a face mask suitable for use with one hand that accommodates the hand in a neutral position while maintaining an adequate seal between the mask and the patient""s face.
The present invention provides an asymmetrical face mask suitable for use with one hand that allows an operator to provide a reliable seal with the patient""s face with his/her hand in a substantially neutral position.
In one aspect, the invention provides an ergonomic face mask for engaging a patient""s face for providing gas to the patient. The mask includes an annular cuff defining an outer periphery of the mask. A dome is attached to the cuff and extends upwardly therefrom. The dome includes a rim asymmetrically positioned on an upper surface of the dome and extending upwardly therefrom. A tubular connector member extends outwardly from the dome for administering the gas.
It is thus one object of the invention to provide an asymmetrical face mask that may be gripped firmly and comfortably with one hand while maintaining an adequate seal with a patient""s face.
In another aspect, the dome defines a first groove located to the right of the rim configured to accept the thumb of a human hand. In another aspect, a second groove is located to the left of the rim configured to receive the index finger of a human hand.
It is thus another object of the invention to provide a face mask that is contoured so as to be comfortably gripped by a user""s thumb and index finger.
In accordance with another aspect, a concavity is disposed at the distal end of the first groove.
It is thus another object to enable the index finger to have a down-slope orientation during use.
In another aspect, the mask includes a second protuberance disposed radially outwardly with respect to the second groove.
It is thus another object to provide a structure that supports the index finger of the operator in the second groove.
In another aspect, the dome includes a third groove that extends behind the rim.
It is thus another object to provide further support for an operator""s hand.
In another aspect, the first, second, and third grooves define a continuous elongated channel.
It is thus another object to provide a continuous groove to define the proper placement of an operator""s hand on the mask.
In another aspect, at least a portion of at least one of the three grooves is textured. In a preferred form, the textured surface includes engravings that extend laterally with respect to the channel.
It is thus another object to enhance the gripping ability of the operator.
In another aspect, a third protuberance is disposed behind the rim and configured to provide support the palm of the operator""s hand.
It is thus another object to provide further ergonomic support for the operator by providing a support to the palm of the hand.
In accordance with another aspect, a first protuberance is located radially outwardly from the first groove and extends radially outwardly towards an outer periphery of the dome.
It is thus another object to provide a support for the operator""s finger to maintain an adequate seal with the patient""s face.
In accordance with another aspect, an extended protuberance is disposed at a distal end of the protuberance and extending to a position adjacent the outer periphery of the dome.
It is thus another object to provide an improved seal with the patient""s face while maximizing comfort to the operator.
In another aspect, the dome is wider on the left side of the rim than the right side.
It is thus another object to provide an adequate surface area on the dome for the ergonomic placement of the operator""s hand.
In another aspect, the cuff is an inflatable cushion configured to provide a seal with the patient""s face.
It is thus another object to enable the cuff to fit a variety of facial structures.
In another aspect, a marker is disposed at least partially within the channel to provide an indication as to the proper placement of the operator""s hand.
It is thus another object to provide a mask whose use is intuitive to an operator.
These and other aspects of the invention are not intended to define the scope of the invention for which purpose claims are provided. In the following description, reference is made to the accompanying drawings, which form a part hereof, and in which there is shown by way of illustration, and not limitation, preferred embodiments of the invention. Such embodiments do not define the scope of the invention and reference must be made therefore to the claims for this purpose.